I seek refuge in Allah’s Perfect Words from His anger
`Amr ibn Shu`aib narrated from his father, from his grandfather, may Allah be pleased with them, that the Messenger of Allah, may the peace and blessings of Allah be upon him, said:
“When one of you is frightened during sleep, then let him say: ‘I seek refuge in Allah’s Perfect Words from His anger, His punishment, and the evil of His creatures, from the whisperings of the Devils, and their presence (A`ūdhu bikalimātillāhit-tāmmati min ghaḍabihī wa `iqābihī wa sharri `ibādih, wa min hamazātish-shayāṭīni wa an yaḥḍurūn).’ For verily, they shall not harm him.”
The words of Allah are complete and involves no deficiency or defect as Imam An-Nawawi said.
It was said: they are the beneficial healing words. There are other scholarly opinions concerning the interpretation of these words; some scholars consider them to be the Quran. Others said: they are the divine names and attributes, and another group of the scholars held the opinion that they are all the words which Allah revealed to his prophets.
The most preponderant opinion - and Allah knows best - that these words are: Subhaan Allah Glory be to Allah, Alhamdu lillah praise be to Allah, la ilah illa Allah there is no god worthy of worship but Allah, and Allahu akbar Allah is the greatest; as each of them indicate the pure monotheism and the most ultimate beauty and perfection.
As for the whisperings of the devils: they put pressure on man, and fill his heart with grief so that they push him to doing evil, and to abstain from goodness. They do their best to hinder him from the straight path. Moreover, they present during one`s death to divert him from uttering la ilah illa Allah.
That is why Allah commanded His Prophet (may the peace and blessings of Allah be upon him) to seek refuge in Allah from the devil's whispers.
If a person is to call upon Allah, then to remember his sins and acknowledge falling short to fulfill the rights of his Lord. The slave shall ask his Lord to protect him against his anger and punishment before asking him any of the demands of this world, even with his heart, for the recognition of guilt and the fear of punishment makes the supplication more worthy to be accepted.